Include attestation status to GitHub and GitLab reports

[javirln]

When running Chainloop's CLI on GitHub or GitLab, we would like the output of the attestation status to be available on the actual job that ran the attestation. This provides an easy way to access the information without needing to navigate through the logs.

In GitHub it's possible to send output to GITHUB_STEP_SUMMARY env variable and for GitLab, the only way possible is creating a file that is then exposed as an artifact to on the job.